Bulk catalysts having increased stability

ABSTRACT

Bulk catalysts that include a Group VI metal, a Group VIII metal, and at least 10-60% of an organic compound based component are formed. The bulk catalysts have increased stability through the use of a stabilizer in the organic compound based component, the use of an improved gas phase sulfidation, or a combination thereof. The bulk catalysts are suitable for hydroprocessing of hydrocarbon feeds.

This Application claims the benefit of U.S. Provisional Application61/195,293 filed Oct. 6, 2008.

FIELD OF THE INVENTION

This invention relates to a bulk metallic catalyst and a correspondingcatalyst precursor comprised of at least one Group VIII metal, at leastone Group VIB metal, and at least one organic complexing agent. Thecatalysts are further characterized as a) including a stabilizer as partof the organic complexing agent, b) being gas-phase sulfided atsufficiently low temperatures, or c) a combination thereof.

BACKGROUND OF THE INVENTION

Increasingly stringent environmental regulations will requiresignificant reductions in the sulfur content of transportation fuels.For example, by the end of this decade, maximum sulfur levels fordistillate fuel will be limited to 10 wppm in Europe and Japan and 15wppm in North America. To meet these ultra-low sulfur requirementswithout expensive modifications to existing refineries, it will benecessary to design a new generation of catalyst that has very highactivity for desulfurization, particularly for distillate fuels at lowto medium pressure.

US Published Patent Application 2008/0132407 describes recentlydeveloped catalysts in an attempt to meet the increased activity needsfor ultra-low sulfur processing. The catalysts described in US2008/0132407 provide an activity benefit over conventional catalysts.However, the long term stability of the catalysts is not proven.

What is needed is a bulk catalyst with improved stability and/orintegrity for long term operation at high activity.

SUMMARY OF THE INVENTION

In an embodiment, a bulk metallic catalyst precursor composition isprovided. The bulk metallic catalyst precursor composition includes aGroup VIII metal, a Group VIB metal, and from about 10 wt. % to about 60wt. % of an organic compound-based component, the catalyst precursorcomposition having a surface area of 16 m²/g or less based on BET,wherein the organic compound-based component is based on at least oneorganic complexing agent and at least one stabilizer. Alternatively, thesurface area of the composition can be 50 m²/g or less.

In another embodiment, a sulfided bulk metallic catalyst is provided.The sulfided bulk metallic catalyst includes a Group VIII metal, a GroupVIB metal, and at least about 10 wt. % carbon. The sulfided bulkmetallic catalyst is formed by sulfiding a catalyst precursorcomposition comprising a Group VIII metal, a Group VIB metal, and fromabout 10 wt. % to about 60 wt. % of a organic compound-based component,the catalyst precursor composition having a surface area of 16 m²/g orless based on BET, wherein the organic compound-based component is basedon at least one organic complexing agent and at least one stabilizer.Alternatively, the catalyst precursor composition can have a surfacearea of 50 m²/g or less.

In still another embodiment, a sulfided bulk metallic catalyst isprovided. The sulfided bulk metallic catalyst includes a Group VIIImetal, a Group VIB metal, and at least about 10 wt. % carbon. Thesulfided bulk metallic catalyst is formed by sulfiding a catalystprecursor composition comprising a Group VIII metal, a Group VIB metal,and from about 10 wt. % to about 60 wt. % of a organic compound-basedcomponent, the catalyst precursor composition having a surface area of50 m²/g or less based on BET, wherein the bulk metallic catalyst isformed by gas-phase sulfidation at a temperature of 350° C. or less.Alternatively, the surface area of the catalyst precursor compositioncan be 16 m²/g or less.

In yet another embodiment, a sulfided bulk metallic catalyst isprovided. The sulfided bulk metallic catalyst includes a Group VIIImetal, a Group VIB metal, and at least about 10 wt. % carbon. Thesulfided bulk metallic catalyst is formed by sulfiding a catalystprecursor composition comprising a Group VIII metal, a Group VIB metal,and from about 10 wt. % to about 60 wt. % of a organic compound-basedcomponent, the catalyst precursor composition having a surface area of50 m²/g or less based on BET. The organic compound-based component isbased on at least one organic complexing agent and at least onestabilizer, and the bulk metallic catalyst is formed by gas-phasesulfidation at a temperature of 350° C. or less. Alternatively, thesurface of the catalyst precursor composition can be 16 m²/g or less.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 provides X-ray Diffraction (XRD) patterns for a bulk CoMocatalyst precursor according to an embodiment of the invention and acomparative CoMo catalyst.

FIGS. 2 a and 2 b provide data related to a Temperature ProgrammedOxidation (TPO) analysis of a catalyst precursor according to anembodiment of the invention.

FIGS. 3 a and 3 b provide data related to a Temperature ProgrammedReduction (H₂-TPR) analysis of a catalyst precursor according to anembodiment of the invention.

FIG. 4 depicts catalyst activity as a function of the amount of organiccomplexing agent used to form a catalyst precursor.

FIGS. 5 and 6 depict Diffuse Reflectance Fourier Transform InfraredSpectroscopy results of studies on catalyst precursors heated accordingto various heating profiles.

FIG. 7 depicts ¹³C NMR spectra for catalyst precursors heated indifferent atmospheres.

FIG. 8 depicts Raman spectra for catalyst precursors subjected tovarious heating profiles.

FIG. 9 depicts XRD of catalyst precursors calcined at varyingtemperatures.

FIG. 10 depicts the effect of sulfiding pressure on catalyst stabilityfor bulk catalysts.

FIG. 11 depicts the effect of gas-phase sulfidation temperature oncatalyst stability for bulk catalysts.

FIG. 12 depicts TEM micrographs for bulk catalysts sulfided at variousgas-phase sulfidation temperatures.

DETAILED DESCRIPTION OF THE INVENTION

The catalysts according to the invention are bulk catalysts formed byheating a catalyst precursor comprised of about 40 wt. % to about 90 wt.% of a Group VIII metal and a Group VIB metal, based on the total weightof the bulk catalyst particles. The weight of metal is measured as metaloxide. The balance of the catalyst precursor weight is an organiccompound-based material. In an embodiment, the Group VIB metal is Mo orW. In another embodiment, the Group VIII metal is Co or Ni. In stillanother embodiment, the Group VIB metal is Mo and the Group VIII metalis Co. In yet another embodiment, the Group VIII metal is a non-noblemetal. Preferably, the catalyst is sulfided using a gas-phasesulfidation procedure at a temperature of 350° C. or less.

In a group of preferred embodiments, the organic compound based materialis based on two separate components. One component is an organiccomplexing agent, as described in detail below. The second component isa stabilizer. The stabilizer can be polyethylene glycol or polyvinylalcohol. The stabilizer increases the stability of the bulk catalyst,thereby preserving the activity of the catalyst during treatment of afeedstock. The use of a stabilizer, the gas-phase sulfidation procedurementioned above, or a combination thereof, is believed to provide a bulkcatalyst with increase stability and/or hydroprocessing activity overtime during processing of a hydrocarbon feed.

Based on X-ray diffraction, it appears that the Group VIII metals andthe Group VIB metals in the catalyst precursor after heating do not havethe long range ordering typically found in materials that are primarilya crystalline oxide. Instead, in some embodiments it appears that themetals are complexed by the organic complexing agent in the catalystprecursor. The metals are complexed by the organic complexing agent whenthe metals and complexing agent are mixed together. The nature of thecomplex may change after one or more heating steps, as the organiccomplexing agent may undergo one or more conversions or reactions toform an organic compound-based component. In an alternative embodiment,the catalyst precursor can have some crystalline or nanocrystallinecharacteristics (based on XRD) in addition to having characteristics ofmetals that are complexed by the organic complexing agent.

The X-ray Diffraction data provided in FIG. 4 of this application wasgenerated under the following conditions. X-ray powder diffractionanalyses of the samples were obtained using a PANalytical X-pert PROMPD, manufactured by PANalytical, Inc., and equipped with a X-Celleratordetector. The 2 theta scan used a Cu target at 45 kV and 40 mA. Thediffraction patterns were taken in the range of 20° to 70° and 20° to70° 2θ. The step size was 0.2 degrees and the time/step was 480 seconds.The remaining X-ray Diffraction data and patterns provided in thisapplication were generated under the following conditions. X-ray powderdiffraction analyses of the samples were obtained using a Bruker D4Endeavor, manufactured by Bruker AXS and equipped with a Vantec-1high-speed detector. The 2 theta scan used a Cu target at 35 kV and 45mA. The diffraction patterns were taken in the range of 2° to 70° 2θ.The step size was 0.01794 degrees and the time/step was 0.1 second.

In this application, an “amorphous” catalyst or catalyst precursorrefers to a catalyst or catalyst precursor that lacks the long rangeorder or periodicity to have peaks in X-ray diffraction spectra that canbe sufficiently distinguished from the background noise in the spectra,such as by determining a ratio of peak intensity versus backgroundnoise. Nanocrystalline catalyst or catalyst precursor refers to catalystor catalyst precursor that has some crystallinity but with a grain sizeof less than 100 nm. This determination is made using X-ray diffractionspectra generated according to the conditions described above.Broadening of X-ray spectra occurs increasingly as particle sizesshrink, such as when grain sizes are <100 nm, resulting in an XRDpattern with broadened or apparently non-existent peaks. It is alsopossible that amorphous or nanocrystalline phases can includecrystalline phases with grain sizes of >100 nm that are resolvable inthe XRD. Without being bound by any particular theory, it is believedthat the high activity of the catalyst systems according to variousembodiments of the invention results from an amorphous and/ornanocrystalline component.

In an embodiment, the bulk catalyst particles according to theinvention, formed by sulfidation of catalyst precursor particles, canhave a characteristic X-ray diffraction pattern of an amorphousmaterial. Generally, it is believed that the long range orderingtypically found in crystalline phases of Group VIII and Group VIB metaloxides and/or sulfides are not present in bulk catalysts formedaccording to the invention. In particular, XRD spectra of catalysts andcatalyst precursors according to the invention either do not showcrystalline phases of CoMo oxides, or alternatively only weakly show thecrystalline CoMo oxide character. Without being bound by any particulartheory, it is believed that the organic complexing agent and/or theresulting organic compound-based component interrupts or inhibitscrystallization of oxides of the Group VIB and Group VIII metals.Instead of forming crystalline oxides with long range ordering, it isbelieved that at least a portion of the bulk catalyst particles have astructure that continues to involve some sort of complex with an organiccompound-based component. This structure may be amorphous and/orcrystalline on a length scale that is not readily resolved by XRD. Thenature of the complexation may differ from the complexation present inthe catalyst precursor. Additionally, at least a portion of the metalspresent in the catalyst can be in the form of metal sulfides, as opposedto complexed metals or amorphous/small crystal metal oxides.

The bulk catalyst precursor compositions of the invention, obtained bymixing of metal reagents with an organic complexing agent and thenheating and/or mixing, have a relatively low surface area (measured byBrunauer-Ernett-Teller method, or BET) of about 16 m²/g or less. Inanother embodiment, the bulk catalyst precursor compositions have asurface area (measured by BET) of less than about 50.0 m²/g, or lessthan about 40.0 m²/g, or less than about 30.0 m²/g, or less than about20.0 m²/g, or less than about 10.0 m²/g, or less than about 9.0 m²/g, orless than about 7.5 m²/g, or less than about 5.0 m²/g, or less thanabout 4.0 m²/g, or less than about 3.0 m²/g, or less than about 2.5m²/g. In still another embodiment, the bulk catalyst precursorcompositions have a surface area of at least about 0.05 m²/g, or atleast about 0.1 m²/g, or at least about 0.25 m²/g. In a preferredembodiment, the bulk catalyst precursor compositions have a surface areaof from about 0.1 m²/g to about 10.0 m²/g.

In alternate embodiments, a binder material may be incorporated into thebulk catalyst precursor composition. For example, suitable binders maybe mixed with the precursor composition and extruded to form particles.For embodiments including a binder, the surface area of the particlesmay be higher, such as about 30 m²/g or less, or about 25 m²/g or less,or about 20 m²/g or less, or to a surface area similar to the precursorwithout binder, as described above.

The molar ratio of Group VIII metal to Group VIB metal ranges generallyfrom about 1 to 10 to about 10 to 1. Expressed as a fractional value,the molar ratio is generally from about 0.1 to about 10. Preferably, theratio of Group VIII metal to Group VIB metal is less than about 3, andmore preferably less than about 2. Preferably, the ratio of Group VIIImetal to Group VIB metal is greater than about 0.33, and more preferablygreater than about 0.5.

It is within the scope of this invention that the catalyst compositionsalso contain any additional component that is conventionally present inhydroprocessing catalysts such as an acidic component, e.g. phosphorusor boron compounds, additional transition metals, rare earth metals,main group metals such as Si or Al, or mixtures thereof. Suitableadditional transition metals are, e.g. rhenium, ruthenium, rhodium,iridium, chromium, vanadium, iron, platinum, palladium, cobalt, nickelmolybdenum, zinc, niobium, or tungsten. All these metals are generallypresent in the sulfided form if the catalyst composition has beensulfided. Prior to sulfidation, at least a portion of one or more metalscan be complexed by the organic compound-based material in the catalystprecursor. After sulfidation, it is believed that at least a portion ofthe sulfided metals are still somehow directly or indirectly bound tothe organic compound-based material (e.g., carbon) in the catalyst.

The bulk metallic catalysts of the present invention are prepared by thecontrolled heating of Group VIII and Group VIB precursor compounds thatare complexed with an organic complexing agent, preferably in the formof an organic acid. Preferably, the organic complexing agent is a metalbinding group or chelating agent. Preferably, the organic complexingagent is a bidentate ligand. Preferably, the organic complexing agent issuitable for forming metal-ligand complexes in solution.

In an embodiment where the catalyst precursor is formed from a solutioncontaining the Group VIII metal, Group VIB metal, and organic complexingagent, it is preferred that both the Group VIII compound and the GroupVIB compound be water soluble salts in the appropriate predeterminedconcentration to yield the desired molar ratios as mentioned above. Themore preferred Group VIII metals are Co and Ni, with Co being the mostpreferred. Preferably, the Group VIII metals are non-noble metals. Themore preferred Group VIB metals are Mo and W, with Mo being the mostpreferred. Non-limiting examples of suitable Co precursor compoundsinclude carbonates, nitrates, sulfates, acetates, chlorides, hydroxides,propionates, glycinates, hydroxycarbonates, acetyl acetates, acetylacetonates, metallic Co(0), Co oxides, Co hydrated oxides, Cocarboxylates (in particular Co glyoxylate), Co citrate, Co gluconate, Cotartrate, Co glycine, Co lactate, Co naphthenate, Co oxalate, Coformate, and mixtures thereof, including ammonium or amine forms of theabove. Preferred molybdenum and tungsten precursor compounds includealkali metal or ammonium molybdate (also peroxo-, di-, tri-, tetra-,hepta-, octa-, or tetradecamolybdate), molybdic acid, phosphomolybdicacid, phosphotungstic acid, Mo—P heteropolyanion compounds, W—Siheteropolyanion compounds, Co—Mo—W heteropolyanion compounds, alkalimetal or ammonium tungstates (also meta-, para-, hexa-, orpolytungstate), acetyl acetonates, and mixtures thereof. In still otherembodiments, any suitable Group VIII or Group VIB metal reagent can beused to prepare Group VIII or Group VIB metal solutions.

Organic acids are a preferred class of organic complexing agent.Non-limiting examples of organic complexing agents suitable for useherein include pyruvic acid, levulinic acid, 2-ketogulonic acid,keto-gluconic acid, thioglycolic acid, 4-acetylbutyric acid,1,3-acetonedicarboxylic acid, 3-oxo propanoic acid, 4-oxo butanoic acid,2,3-diformyl succinic acid, 5-oxo pentanoic acid, 4-oxo pentanoic acid,ethyl glyoxylate, glycolic acid, glucose, glycine, oxamic acid,glyoxylic acid 2-oxime, ethylenediaminetetraacetic acid,nitrilotriacetic acid, N-methylaminodiacetic acid, iminodiacetic acid,diglycolic acid, malic acid, gluconic acid, acetylacetone, and citricacid. Preferred organic acids are glyoxylic acid, oxalacetic acid,2-ketogulonic acid, alpha-ketoglutaric acid, 2-ketobutyric acid, pyruvicacid, keto-gluconic acid, thioglycolic acid, and glycolic acid. Mostpreferred are glyoxylic acid and oxalacetic acid.

In another embodiment, the organic complexing agent is an organic acidthat contains a —COOH functional group and at least one additionalfunctional group selected from carboxylic acid —COOH, hydroximate acid—NOH—C═O, hydroxo —OH, keto —C═O, amine —NH2, amide: —CO—NH2, imine:—CNOH, epoxy: ═COC═, or thiol: —SH. Preferably, the organic complexingagent is a bidentate ligand.

In preferred embodiments, an additional stabilizer is used inconjunction with the organic complexing agent. In such embodiments, astabilizer is used in addition to the specified amount of organiccomplexing agent. The stabilizer can be polyethylene glycol (PEG) orpolyvinyl alcohol. The amount of stabilizer can be expressed relative tothe amount of organic complexing agent. The ratio of the amount oforganic complexing agent to the amount of stabilizer can be 20:1 orless, or 10:1 or less, or 5:1 or less, or 4:1 or less. The ratio oforganic complexing agent to stabilizer can be at least 3:2, or at least2:1

The process for preparing the catalysts of the present inventioncomprises multiple steps. The first step is a mixing step wherein atleast one Group VIII metal reagent, at least one Group VIB metalreagent, and at least one organic complexing agent are combinedtogether. In an embodiment, one or more of the metal reagents andorganic complexing agent can be provided in the form of solutions, suchas aqueous solutions. In another embodiment, one or more of the metalreagents and organic complexing agent can be provided in the form ofslurries. In still another embodiment, one or more of the metal reagentsand organic complexing agent can be provided in the form of a solidmaterial. Those of skill in the art will recognize that still otherforms of providing the organic complexing agent and metal reagent arepossible, and that any suitable form (solution, slurry, solid, etc.) canbe used for each individual reagent and/or organic complexing agent in agiven synthesis.

The metal reagents and organic complexing agent are mixed together toform a precursor mixture. In an embodiment where one or more of themetal reagents or organic complexing agent are provided as a solution orslurry, mixing can involve adding the metal reagents and organiccomplexing agent to a single vessel. If one or more of the metalreagents and organic complexing agent are provided as solids, mixing caninclude heating the organic complexing agent to a sufficient temperatureto melt the complexing agent. This will allow the organic complexingagent to solvate any solid metal reagents. Preferably, a stabilizer isalso added to the mixture of metal reagents and organic complexingagent. The stabilizer can be added to the mixture at any convenienttime.

The temperature during mixing is preferably from ambient temperature tothe boiling point of the solvent. The preparation can be performed inany suitable way. For example, in embodiments involving solutions and/orslurries, separate solutions (or slurries) can be prepared from each ofthe catalytic components. That is, a Group VIII metal compound in asuitable solvent and a Group VIB metal in a suitable solvent can beformed. Non-limiting examples of suitable solvents include water and theC₁ to C₃ alcohols. Other suitable solvents can include polar solventssuch as alcohols, ethers, and amines. Water is a preferred solvent. Itis also preferred that the Group VIII metal compound and the Group VIBcompound be water soluble and that a solution of each be formed, or asingle solution containing both metals be formed. The organic complexingagent can be prepared in a suitable solvent, preferably water. The threesolvent components can be mixed in any sequence. That is, all three canbe blended together at the same time, or they can be sequentially mixedin any order. In an embodiment, it is preferred to first mix the twometal components in an aqueous media, than add the organic complexingagent.

The process conditions during the mixing step are generally notcritical. It is, e.g., possible to add all components at ambienttemperature at their natural pH (if a suspension or solution isutilized). It is generally preferred to keep the temperature below theboiling point of water, i.e., 100° C. to ensure easy handling of thecomponents during the mixing step. However, if desired, temperaturesabove the boiling point of water or different pH values can be used. Inan embodiment where the organic complexing agent is an acid or basehaving a conjugate base/acid, the pH of the mixture can be adjusted todrive the acid/base equilibrium toward a desired form. For example, ifthe organic complexing agent is an acid, the pH of the solution can beraised to drive the equilibrium toward formation of more of theconjugate base. If the reaction during the mixing step is carried out atincreased temperatures, the suspensions and solutions that are addedduring the mixing step are preferably preheated to an increasedtemperature which can be substantially equal to the reactiontemperature.

The amount of metal precursors and organic complexing agent (includingany stabilizer) in the mixing step should be selected to achievepreferred ratios of metal to organic compound-based material in thecatalyst precursor after heating. These preferred ratios result inhighly active bulk catalysts. For example, the ratio of organic acid tototal metal in the mixed solution (or other mixture of metal reagentsand organic complexing agent) should reach a minimum level that resultsin a highly active catalyst.

In an embodiment, the amount of organic complexing agent, pluspreferably a stabilizer, used in the mixed solution should be enough toprovide at least about 10 wt % of organic compound-based material in thecatalyst precursor formed after heating, or at least about 20 wt %, orat least about 25 wt %, or at least about 30 wt %. In anotherembodiment, the amount of organic complexing agent and stabilizer usedin the mixed solution should provide less than about 60 wt % of organiccompound-based material in the catalyst precursor formed after heating,or less than about 40 wt %, or less than about 35 wt %, or less thanabout 30 wt %. Preferably, the amount of organic complexing agent andstabilizer used in the mixed solution is enough to provide between about20 wt % and about 35 wt % of organic compound-based material in theresulting catalyst precursor. A desired amount of organic compound-basedmaterial in the catalyst precursor can be achieved based on the amountof organic complexing agent to metal ratio in the mixed solution andbased on the thermal activation conditions used to form the catalystprecursor. The term “organic compound-based material” refers to thecarbon containing compound present in either the catalyst precursorafter heating, or in the catalyst after sulfidation. The organiccompound-based material is derived from the organic complexing agent,but may be modified due to heating of the catalyst precursor and/orsulfidation of the precursor to form the catalyst. Note that theeventual form of the organic compound-based material may include carbonnot traditionally considered as “organic”, such as graphitic oramorphous carbon. The term organic compound-based material used herespecifies only that the carbon was derived originally from the organiccomplexing agent and/or another organic carbon source used in formingthe catalyst precursor.

For this invention, the weight percentage of organic compound-basedmaterial in the catalyst precursor was determined by performing aTemperature Programmed Oxidation on the catalyst precursor under thefollowing conditions. Temperature Programmed Oxidation using TGA/MS wasperformed on dried and heated samples. The TGA/MS data was collected ona Mettler TGA 851 thermal balance which was interfaced with a quadrupolemass spectrometer equipped with a secondary electron multiplier. Between20 and 25 mg of sample was heated at 4° C./min from ambient temperatureto 700° C. in flowing 14.3% O₂ in He (77 cc/min) at one atmosphere totalpressure. In the TGA/MS experiments, the effluent gas was carried overto the MS instrument via a capillary line and specific m/e fragmentssuch as 18 (H₂O), 44 (CO₂), 64 (SO₂) were analyzed as markers for thedecomposition products and qualitative correlation with gravimetric/heateffects.

The weight percentage of material lost during a TPO procedure representsthe weight percentage of organic compound-based material. The remainingmaterial in the catalyst precursor is considered to be metal in the formof some type of oxide. For clarity, the weight percent of metal presentin the catalyst precursor is expressed as metal oxide in the typicaloxide stoichiometry. For example, weights for cobalt and molybdenum arecalculated as CoO and MoO₃, respectively.

A similar calculation can be performed to determine the weightpercentage of organic compound-based component in the catalyst formedafter sulfidation. Once again, the weight percent of organiccompound-based component is determined by TPO, according to the methoddescribed above. The remaining weight in the catalyst corresponds tometal in some form, such as oxide, oxysulfide, or sulfide.

The amount of organic complexing agent used in the mixed solution shouldalso be enough to form metal-organic complexes in the solution underreaction conditions. In an embodiment where the complexing agent is anorganic acid, the ratio of carboxylic acid groups of the organic acidsto metals can be at least about 0.33, or at least about 0.5, or at leastabout 1 (meaning that about the same number of carboxylic acid groupsand metal atoms are present), or at least about 2, or at least about 3.In another embodiment, the ratio of carboxylic acid groups to metals canbe 12 or less, or 10 or less, or 8 or less.

In another embodiment, the molar ratio used in the mixing solution oforganic complexing agent to metals is about 6.0 to 1 or less, or about5.5 to 1 or less, or about 5.0 to 1 or less, or about 4.8 to 1 or less,or about 4.6 to 1 or less. In another embodiment, the molar ratio usedin the mixing solution of organic complexing agent to metals is about0.5 to 1 or more, or about 1 to 1 or more, or is about 1.5 to 1 or more,or about 2 to 1 or more, or about 2.5 to 1 or more, or about 3.0 to 1 ormore, or about 3.5 to 1 or more.

In a preferred embodiment, the molar ratio of the Group VIII metal tothe Group VIB metal is at least about 0.1, or at least about 0.2, or atleast about 0.33, or at least about 0.5. In another preferredembodiment, the molar ratio of the Group VIII metal to the Group VIBmetal is about 0.9 or less, or about 0.6 or less.

The second step in the process for preparing the catalysts of thepresent invention is a heating step. In an embodiment, the heating stepis used to remove water from the mixture. In another embodiment, theheating step is used to form an organic compound-based component in thecatalyst precursor. The organic compound-based component is the productof heating the organic complexing agent, as well as any stabilizer, usedin the mixing solution. The organic complexing agent may besubstantially similar to the organic compound-based component, or theorganic compound-based component may represent some type ofdecomposition product of the organic complexing agent. Alternatively,without being bound by any particular theory, heating of the organiccomplexing agent may result in cross linking of the complexing agent toform an organic compound-based component.

It is within the scope of this invention that the heating and/or dryingbe performed in multiple phases according to a heating profile. In anembodiment, the first phase of the heating profile is a partial dryingphase, preferably performed at a temperature from about 40° C. to about60° C. in a vacuum drying oven for an effective amount of time. Aneffective amount of time corresponds to a time sufficient to removewater to the point of gel formation. Typically it is believed a gel willform when from about 80% to about 90% of the water is removed. Inembodiments where the mixture of the metal reagents and the organiccomplexing agent is in the form of a solution or slurry, it is preferredto agitate the mixture of metal reagents, organic complexing agent, andoptional stabilizer components at about ambient temperature for aneffective period of time to ensure substantial uniformity anddissolution of all components prior to heating. Alternatively, inembodiments where the organic complexing agent is provided as a solid,an initial heating phase can correspond to heating used to melt theorganic complexing agent. The temperature of the mixture can bemaintained for an effective amount of time to allow the melted organiccomplexing agent to solvate and/or mix with the metal reagents.

In an embodiment, the next heating or drying phase in the heatingprofile is to raise the temperature to about 110° C. to about 130° C.,preferably from about 110° C. to about 120° C., to drive off additionalwater to the point that high temperature heating can be done withoutcausing boiling over and splashing of solution. At this point the gelwill be transformed into a solidified material. The effective amount oftime to form the dried material, that is from gel formation tosolidified material, can be from seconds to hours, preferably from about1 minute to several days, more preferably from about 1 minute to 24hours, and still more preferably from about 5 minutes to about 10 hours.The gel, upon solidification and cooling to room temperature can alsotake the form of a black rubbery solid material. The gel or solidifiedmaterial can be brought to ambient temperature and saved for futureheating at higher temperatures. In the alternative, the gel orsolidified material can be used as a catalyst precursor at this stage.

It is within the scope of this invention to grind the solid material toa powder before or after thermal activation. The grinding can take placeprior to any heating steps at temperatures of about 275° C. or greater,or the grinding can take place after heating to about 275° C. orgreater. Any suitable grinding technique can be used to grind the solidmaterial.

The catalyst precursor can be subjected to a further heating stage to ispartially decompose materials within the catalyst precursor. Thisadditional heating stage can be carried out at a temperature from about100° C. to about 500° C., preferably from about 250° C. to about 450°C., more preferably from about 300° C. to about 400° C., and still morepreferably from about 300° C. to about 340° C., for an effective amountof time. This effective amount of time will range from about 0.5 toabout 24 hours, preferably from about 1 to about 5 hours. In anotherembodiment, heating can be accomplished by ramping the temperature in afurnace from room temperature to about 325° C. in one hour. In anembodiment, the heating (including possible decomposition) can becarried out in the presence of a flowing oxygen-containing gas such asair, a flowing inert gas such as nitrogen, or a combination ofoxygen-containing and inert gases. In another embodiment, the heatingcan be carried out in the atmosphere present in the furnace at thebeginning of the heating process. This can be referred to as a staticcondition, where no additional gas supply is provided to the furnaceduring heating. The atmosphere in the furnace during the staticcondition can be an oxygen-containing gas or an inert gas. It ispreferred to carry out the heating in the presence of an inert gasatmosphere, such as nitrogen. Without being bound by any particulartheory, the material resulting from this additional heating mayrepresent a partial decomposition product of the organic complexingagent and/or stabilizer, resulting in the metals being complexed by anorganic compound-based material or component.

As previously mentioned, the heating step can be performed in a varietyof ways. The heating step can start with one or more initial heatingstages at a lower temperature followed by heating at a temperature ofabout 275° C. or greater. In other embodiments, the heating profile caninclude only temperatures of about 130° C. or lower, or the heatingprofile can include immediately ramping the temperature to about 275° C.or greater, or about 325° C. or greater. Preferably, the preparationconditions can be controlled and designed so that the mixed solutiondoes not go through violent evaporation, spill or interruption duringthe entire heating profile. Such embodiments typically involve aninitial heating at a temperature below 100° C. However, in anotherembodiment, the heating profile can include conditions that lead torapid evaporation while the catalyst precursor still contains asubstantial amount of water. This can lead to boiling or splashing ofthe mixture used to form the catalyst precursor. While boiling orsplashing of the mixture for forming the catalyst precursor isinconvenient, it is believed that catalyst precursor according to theinvention will still be formed under these conditions.

In contrast to conventional hydroprocessing catalysts, which typicallyare comprised of a carrier impregnated with at least one Group VIIImetal and at least one Group VIB metal, the catalysts of the presentinvention are bulk catalysts.

Without being bound by any particular theory, it is believed that theorganic complexing agent and/or the resulting organic-compound basedcomponent plays a role in the unexpected high activity of the finalcatalysts. It is believed that the organic complexing agent and/or theresulting organic compound-based component either assists instabilization of the metal particles and/or directly interacts withmetal active sites and prevents the metal from agglomerating. In otherwords, the organic complexing agent and/or organic compound-basedcomponent enhances the dispersion of the active sites. When a catalystprecursor is formed with an amount of organic compound-based componentthat is less than the desired range, the activity of the resultingcatalyst is lower.

A bulk powder catalyst precursor composition according to the invention,obtained after grinding and heating, can be directly formed into shapessuitable for a desired catalytic end use. Alternately, the bulk powdercan be mixed with a conventional binder material then formed into thedesired shapes. If a binder is used, it may be either introduced beforeor after decomposition (heating) of the mixture used to form thecatalyst precursor. Examples of potential binders include Actigel clay,available from Active Minerals International of Hunt Valley, Md.; Nyacol2034 DI, available from Nyacol Nano Technologies, Inc. of Ashland,Mass.; Dupont™ Tyzor® LA, which is a lactic acid chelated titaniumbinder; or a Si-resin, such as Q-2230 available from Dow Corning. Instill another embodiment, a binder precursor, such as silicic acid, Siacetate, or Al acetate, may be added to the mixture used forsynthesizing the catalyst precursor.

The third step in the preparation of the catalysts of the invention is asulfidation step. Sulfidation is generally carried out by contacting thecatalyst precursor composition with a sulfur containing compound, suchas elemental sulfur, hydrogen sulfide or polysulfides. Sulfidation canalso be carried out in the liquid phase utilizing a combination of apolysulfide, such as a dimethyl disulfide spiked hydrocarbon stream, andhydrogen. The sulfidation can be carried out subsequent to thepreparation of the bulk catalyst composition but prior to the additionof a binder, if used.

If the catalyst composition is used in a fixed bed process, sulfidationis preferably carried out subsequent to the shaping step. Sulfidationmay be carried out ex situ or in situ. For ex situ sulfidation,sulfidation is carried out in a separate reactor prior to loading thesulfided catalyst into the hydroprocessing unit. In situ sulfidation ispreferred and for in situ sulfidation the sulfidation is carried out inthe same reactor used for hydroprocessing.

In an embodiment, the sulfidation can be a gas phase sulfidationprocess. Due to the nature of the catalyst precursor, liquid phasesulfidation methods can lead to a reduction in the mass and/or integrityof the catalyst. However, gas phase sulfidation methods have a tendencyto increase the stack height of active material in a catalyst, whichleads to a corresponding drop in activity. This loss in activity can beavoided by using a gas phase sulfidation method with a sulfidationtemperature of 350° C. or less. This is in contrast to some conventionalgas phase sulfidation methods, which are typically performed at 400° C.

In another embodiment, the sulfidation step can be a liquid sulfidation.In such an embodiment, the bulk catalyst can be sulfided by exposing thecatalyst to a feedstock spiked with 1.36% by weight of dimethyldisulfide. Alternatively, the spiking level of dimethyl disulfide can bebetween 0.5 and 2.5% by weight. The catalyst can be exposed to the feedat a pressure of 500 psig at a LHSV of 1.0 and hydrogen flow rate of 700scf/B. Preferably, the catalyst can be exposed to the feed for aninitial period of time, such as 18 hours, at a temperature of 425° F.(218° C.), followed by a second period of time, such as 24 hours, at atemperature of 625° F. (329° C.). In other embodiments, otherconventional methods of sulfidation can be used.

In still another embodiment involving liquid sulfidation, the catalystcan be sulfided using temperature and pressure conditions that are moresevere than the expected eventual processing conditions. For example, ifthe sulfided catalyst will be used for processing a feedstock at apressure of 150 psig, the sulfidation can be performed at a higherpressure to reduce the time needed to achieve sulfidation of thecatalyst.

In various embodiments, the catalyst formed after sulfidation isbelieved to have at least in part a structure involving complexation oranother interaction of metals by/with an organic compound-basedcomponent. The nature of the organic compound-based component in thesulfided catalyst may differ from the organic compound-based componentin the catalyst precursor and the organic complexing agent used in theinitial mixture to form the catalyst precursor. Note that in theExamples below, the carbon and sulfur species in the sulfided catalystappear to oxidize and leave the catalyst at a similar time inTemperature Programmed Oxidation studies. One possible interpretationfor these TPO studies is the presence of a complex (or some other typeof interaction) between the organic compound-based component and metalsin at least a portion of the catalyst structure.

In an embodiment, the carbon content of the catalyst after sulfidationis at least 10 wt % or at least 12 wt %. In another embodiment, thecarbon content of the catalyst after sulfidation is 25 wt % or less or20 wt % or less.

After sulfidation, at least a portion of the metal in the catalyst willbe in a sulfided form. In particular, the Group VIB metal will formstacks of sulfided metal believed to have a MeS₂ stoichiometry, where Merepresents the Group VIB metal. For example, if Mo is the Group VIBmetal, stacks of MoS₂ will be formed. In catalysts formed according tothe invention, the average stack height of the sulfided Group VIB metalwill be from about 1.1 to about 2. In another embodiment, the averagestack height will be at least 1.1, or at least 1.2, or at least 1.3, orat least 1.4, or at least 1.5. In still another embodiment, the averagestack height will be 2.2 or less, or 2.1 or less, or 2.0 or less, or 1.9or less. Without being bound by any particular theory, it is believedthat a lower stack height corresponds indirectly to increased activity.

The catalyst compositions of the present invention are particularlysuitable for hydroprocessing hydrocarbon feeds. Examples ofhydroprocessing processes include hydrogenation of unsaturates,hydrodesulfurization, hydrodenitrogenation, hydrodearomatization andmild hydrocracking. Preferred are hydrodesulfurization andhydrodenitrogenation. Conventional hydroprocessing conditions includetemperatures from about 250° to 450° C., hydrogen pressures of from 5 to250 bar, liquid hourly space velocities of from 0.1 to 10 h⁻¹, andhydrogen treat gas rates of from 90 to 1780 m³/m³ (500 to 10000 SCF/B).

Feedstocks on which the present invention can be practiced are thosepetroleum feedstreams boiling in the distillate range. This boilingrange will typically be from about 140° C. to about 360° C. and includesmiddle distillates, and light gas oil streams. Non-limiting examples ofpreferred distillate streams include diesel fuel, jet fuel and heatingoils. The feedstocks can contain a substantial amount of nitrogen, e.g.at least 10 wppm nitrogen, and even greater than 1000 wppm, in the formof organic nitrogen compounds. The feedstocks can also contain asignificant sulfur content, ranging from about 0.1 wt. % to 3 wt. %, orhigher.

The hydroprocessing of the present invention also includes slurry andebullating bed hydrotreating processes for the removal of sulfur andnitrogen compounds, and the hydrogenation of aromatic molecules presentin light fossil fuels, such as petroleum mid-distillates, particularlylight catalytic cycle cracked oils (LCCO). Distillates derived frompetroleum, coal, bitumen, tar sands, or shale oil are likewise suitablefeeds. Hydrotreating processes utilizing a slurry of dispersed catalystsin admixture with a hydrocarbon feed are generally known. For example,U.S. Pat. No. 4,557,821 to Lopez et al discloses hydrotreating a heavyoil employing a circulating slurry catalyst. Other patents disclosingslurry hydrotreating include U.S. Pat. Nos. 3,297,563; 2,912,375; and2,700,015. The slurry hydroprocessing process of this invention can beused to treat various feeds including mid-distillates from fossil fuelssuch as light catalytic cycle cracking oils (LCCO).

Hydrogenation conditions include reactions in the temperature range ofabout 100° C. to about 350° C. and pressures from about five atmospheres(506 kPa) and 300 atmospheres (30,390 kPa) hydrogen, for example, 10 to275 atmospheres (1,013 kPa to 27,579 kPa). In one embodiment thetemperature is in the range including 180° C. and 320° C. and thepressure is in the range including 15,195 kPa and 20,260 kPa hydrogen.The hydrogen to feed volume ratio to the reactor under standardconditions (25° C., 1 atmosphere pressure) will typically range fromabout is 20-200, for water-white resins 100-200.

Process conditions applicable for the use of the catalysts describedherein may vary widely depending on the feedstock to be treated. Thus,as the boiling point of the feed increases, the severity of theconditions will also increase. The following table (Table 1) serves toillustrate typical conditions for a range of feeds.

TABLE 1 TYPICAL SPACE BOILING PRESS, VELOCITY FEED RANGE ° C. TEMP. ° C.BAR V/V/HR H₂ GAS RATE SCF/B naphtha  25-210 100-370 10-60   0.5-10100-2,000 diesel 170-350 200-400 15-110 0.5-4 500-6,000 heavy gas oil325-475 260-430 15-170 0.3-2 1000-6,000  lube oil 290-550 200-450  6-2100.2-5  100-10,000 residuum 10-50% > 575 340-450  65-1100 0.1-12,000-10,000 

The following examples will serve to illustrate, but not limit thisinvention.

Example 1A Catalyst Precursor Synthesis

Bulk CoMo catalysts were prepared by a controlled heating processaccording to an embodiment of the invention. A 1 M Mo aqueous solutionwas prepared by dissolving the appropriate amount of ammoniumheptamolybdate tetrahydrate (AHM) in distilled water. A 1 M Co aqueoussolution was also prepared by dissolving the appropriate amount ofcobalt acetate tetrahydrate in distilled water. A 4.5 M glyoxylic acidsolution was prepared by a 1:1 dilution with distilled water of 50%glyoxylic acid aqueous solution.

A mixture was prepared by mixing together appropriate amounts of theabove three solutions. The resulting solution had a reddish color. Theratio of Mo to Co in the solution was 2:1. Two bulk catalyst precursormixtures were prepared. One catalyst precursor mixture had a molar ratioof glyoxylic acid/(Mo+Co) of 4.8, and is designated Catalyst PrecursorA. A second catalyst precursor mixture designated Catalyst Precursor Bwas prepared having a molar ratio of glyoxylic acid/(Mo+Co) of 6. Thecatalyst precursor mixtures were heated at 55° C. for about 4 hours,then at 120° C. for about an additional 4 hours. The result for eachcatalyst precursor was a black viscous substance. The black viscoussubstance was then cooled to room temperature wherein it solidified. Thesolidified black substance was ground to a powder and placed in a tubefurnace whereupon the temperature was ramped from about room temperatureto about 325° C. in one hour. The catalyst precursor compositions werethen heated at a temperature of about 325° C. in air for about 4 hours.

Samples of the two catalyst precursor powders were crushed into finesusing an agate mortar and pestle. A portion of the precursor powderswere sulfided to produce catalyst powder.

The BET surface area and carbon content were measured for the catalystprecursor compositions of Catalyst Precursor A and Catalyst Precursor Bas well as for a CoMo catalyst precursor prepared similarly, but withoutthe use of an organic acid (Comparative Catalyst 1). The results areshown in Table 2 below. X-ray diffraction showed that both samples ofthe bulk catalyst precursors of the present invention were amorphous incharacter, and do not exhibit the long range order typically observed inXRD when large particles of crystallized phases are present. The X-raydiffraction pattern for Comparative Catalyst 1 showed crystallized MoO₃and CoMoO₄, which are typically regarded as undesirable catalystprecursors for hydrotreating processes. It is believed that residualcarbon inside the catalyst precursors of the present inventioninterrupts the crystallization of CoMo oxides so that CoMo oxidecrystals either are not present or are present as small crystals thatintroduce little or no crystalline character into XRD spectra.

TABLE 2 BET SA Carbon Content Catalyst (m²/g) (wt. %) Catalyst PrecursorB 15.6 23.8 CoMo-6-Gly Catalyst Precursor A <1 21.9 CoMo-4.8-GlyComparative Catalyst 1 20 0.22 CoMo Prepared Without Organic Acid

It can be seen from Table 2 above that the bulk CoMo-6-Gly andCoMo-4.8-Gly catalyst precursors have relatively low surface areas. Inparticular, catalyst precursor CoMo-4.8 has a surface area less than 1m²/g. After heating, both catalyst precursors of this invention containsubstantial amounts of carbon of about 22 to 24 wt. %. The carboncontent of the catalyst precursors of this invention is a function ofthe heating conditions the catalysts experienced, i.e., the time and thetemperature of the heating profile, as well as the ratios of glyoxylicacid/(Mo+Co) metal. The carbon content in the bulk CoMo catalystprecursors influences the morphology of the CoMo in such precursors andthe resulting hydrodesulfurization catalytic activities of the sulfidedcatalysts.

Example 1B Catalyst Precursor Synthesis

1 M solutions of ammonium heptamolybdate tetrahydrate and cobalt acetatetetrahydrate were used to form additional catalyst precursors. Asolution containing 5.7 wt % AHM, 4.0 wt % Co Acetate, and 17.3 wt %glyoxylic acid was formed by mixing appropriate amounts of the 1 M Moand Co solutions with a solution containing 25 wt % of glyoxylic acid.The molar ratio of R/(Co+Mo) was 4.8. After heating, the solution yieldto solid was about 8.6%.

Separately, a solution containing 12.8 wt % AHM, 9.1 wt % Co Acetate,and 39.1 wt % glyoxylic acid was formed by mixing appropriate amounts ofthe 1 M Mo and Co solutions with a solution containing 50 wt % ofglyoxylic acid. The molar ratio of R/(Co+Mo) was 4.8. After heating, thesolution yield to solid was about 19.4%.

Example 1C Catalyst Precursor Synthesis

This example is directed to the synthesis of bulk trimetallic NiCoMo. Abulk trimetallic NiCoMo catalyst was prepared by a controlled heatingprocess according to the invention. 200 mg NiO, 200 mg Co(OH)₂ and 1 gH₂MoO₄ were each dissolved/suspended in water in separate containers. A50 wt. % glyoxylic acid solution was added to each container such thatthe concentration of acid in each container was 15 wt. %. The Ni, Co,and Mo solutions were combined and 6 ml 30% H₂O₂ added to the combinedsolution. The sample was heated at 250 C for 4 hours to yield the bulktrimetallic NiCoMo catalyst precursor.

Example 2 Catalyst Precursor Characterization

An X-ray Diffraction (XRD) analysis was performed on a CoMo basedcatalyst precursor synthesized according to an embodiment of theinvention. The resulting XRD spectrum is shown in FIG. 1. As shown inFIG. 1, the CoMo based catalyst precursor has an amorphous XRD spectrum.It is believed that the organic compound-based component in the CoMocatalyst precursor interrupts the crystallization process, resulting ina CoMo catalyst precursor that does not have a detectable crystallinephase. In an alternative embodiment of the invention, a crystallinephase may be detectable in a catalyst precursor, but only as a portionof the catalyst precursor, resulting in XRD spectra with somecrystalline character and some amorphous character. This is in contrastto the XRD spectrum of a bulk CoMo material (Comparative Catalyst 1)that was prepared without using an organic complexing agent, but thatwas otherwise prepared similarly to the catalyst precursors of theinvention. The XRD spectrum for the bulk comparative CoMo material showsa crystalline morphology, including peaks that appear to represent MoO₃and CoMoO₄.

Example 3 Temperature Programmed Oxidation of Catalyst Precursor

A temperature programmed oxidation (TPO) study was carried out tounderstand the nature of organic compound-based component of a catalystprecursor synthesized according to the procedure for Catalyst A inExample 1. FIG. 2 a shows that the catalyst precursor loses about 30 wt% of weight as the catalyst precursor is exposed to increasingtemperatures up to 650° C. FIG. 2 b shows a mass spectrometrycharacterization of the products generated from the catalyst precursorsample as a function of temperature. The primary products generatedduring the TPO study were CO₂ and H₂O. Based on FIGS. 2 a and 2 b, it isbelieved that at 650° C. all of the carbon has been removed from thecatalyst precursor sample. The TPO study, in combination with theTemperature Programmed Reduction study described in Example 4, indicatesthat the organic compound-based component is composed of at leastcarbon, hydrogen, and oxygen.

Example 4 Temperature Programmed Reduction of Catalyst Precursor

FIG. 3 shows the results from a Temperature Programmed Reductionanalysis (H₂-TPR) of a catalyst precursor synthesized according to theprocedure for Catalyst Precursor A in Example 1. The H₂-TPR analysis wascarried out in a 5% H₂/He atmosphere, with a temperature change rate of10° C. per minute. The results of the H₂-TPR study are shown in FIGS. 3a and 3 b. FIG. 3 a shows the total weight loss as measured bythermo-gravimetric analysis. By the time the sample reached 700° C.,almost 40% of the weight of the precursor sample was removed. As shownin FIG. 3 b, this weight loss was in the form of H₂O, CO₂, and COreleased from the precursor sample. The species released from the sampleare believed to represent removal of the organic compound-basedcomponent and/or conversion of some metal oxides into lower oxidationstates.

Note also that FIGS. 2 a, 2 b, 3 a, and 3 b indicate that removal of theorganic compound-based component is minimal until a temperature near400° C. is achieved. Based on this, it is preferred that sulfidation ofcatalyst precursors, which also occurs in a reducing environment, shouldtake place at a temperature of less than about 400° C., preferably lessthan about 350° C. For example, one preferred sulfidation temperature isabout 325° C.

Example 5 Heating Step Variations

Catalyst precursors were prepared similar to Catalyst Precursor A exceptthat different heating steps were performed on four different samples infour different atmospheres—air, nitrogen, hybrid (mixture of air andnitrogen), and without air-flow (statically heated). In the hybridatmosphere heating, the furnace was ramped in a nitrogen atmosphere fromabout room temperature to about 325° C. in one hour and held at 325° C.under nitrogen for 2 additional hours, then the atmosphere was graduallyswitched to air in a period of about 2 hours. The final treatment wascarried out in air at 325° C. for two hours. The surface area and carboncontent was measured for each sample and the results are presented inTable 3 below.

TABLE 3 Surface Areas and C-Contents of Bulk CoMo Catalyst PrecursorsBET SA C Content CoMo-Glyoxylic Acid Catalysts (m²/g) (wt %) Air heatingat 617° F. 9.7 22.0 Hybrid heating at 617° F. <0.5 22.8 N₂ heating at617° F. 0.7 22.7 Statically heating at 617° F. 0.8 22.0

It can be seen from Table 3 above that the bulk CoMo catalyst precursorshave relatively low surface areas. Except for the bulk CoMo catalystprecursor heated in air, which has less than 10 m²/g surface area, theother catalyst precursors have surface area less than 1 m²/g. Afterheating in air, and/or nitrogen, and/or hybrid (a mixture of air andN₂), and/or without air-flow (static atmosphere), all catalystprecursors contain substantial amounts of carbon, about 22 to 23 wt %.

Example 6 Characterization of Activity Relative to Organic Content

FIG. 4 shows the relative activity of bulk CoMo catalysts created usingvarying amounts of organic complexing agent. The data in FIG. 4 wasgenerated by creating various catalyst precursors using glyoxylic acidas the organic complexing agent. As shown in FIG. 4, catalyst precursorshaving a ratio of organic complexing agent to metal of less than about2:1 result in catalysts with a substantially lower activity. Catalystswith a organic complexing agent to metal ratio of greater than about2:1, and preferably greater than about 3:1, exhibit a relative activitythat is 4 to 6 times greater than the activity of the catalysts with aratio below about 2:1.

Example 7 Additional Catalyst Precursor Characterization

FIG. 5 depicts DRIFTS spectra of bulk CoMoC material thermally treatedat 325° C. in air and N₂. Diffuse Reflectance Infrared Fourier TransformSpectroscopy (DRIFTS) spectra were collected on a Nicolet 670 FTIRspectrometer equipped with a liquid N₂-cooled MCT detector. The spectrawere recorded with a resolution of 8 cm⁻¹. A powder sample of bulk CoMowas loaded into a controlled atmosphere DRIFTS cell (Thermo SpectraTech) fitted with ZnSe windows. The cell was connected to a gas systemable to feed in dry He and other gases. A programmed furnace was used tocontrol the sample temperature. Typically the as prepared sample wastreated in He at 120° C. at 2° C./min and held for 1 hour to dry thesample.

As shown by FTIR, the organic compound-based materials present in thecatalyst precursors are similar. The C═O vibration characteristic ofaldehyde and acid groups are observed in the range of 1700 to 1900 cm⁻¹,while the OCO vibration characteristic of carboxyl groups can be seen inthe range of 1400 to 1650 cm⁻¹. The shift in the C═O vibration can beattributed to the complexation of the metal sites (e.g. Co or/and Momoieties) with organic complexing agent (e.g. glyoxylic acid) functionalgroups (aldehyde and carboxylic). Other species such as aliphatic CH₂ in1970-2880cm⁻¹) and nitrile/isocyanate (2220-2191 cm⁻¹) are evidenced.There is also evidence of aromatic-type moiety ═CH (3100 cm⁻¹) andspecies with an —OH type group at 3300 cm⁻¹. It is believed that thevarious surface species are associated with the organic acid (orcomplexing agent) forming complexes with the metal sites. Chemicaltransformation to produce new surface species during thermal activationmay also occur. For example, the presence of nitrile/isocyanate can beexplained by NH₃ reaction with glyoxylic acid. NH₃ can be formed duringthe decomposition of ammonium cations present in the molybdenumprecursor.

FIG. 6 provides a comparison of DRIFTS spectra of bulk CoMo materialsfrom different stages of thermal treatment. As shown in FIG. 5, the keyfeatures observed for the catalyst precursors appear to be presentthrough entire heating process up to 325° C. This indicates thecomplexes formed between organic acid and metals prior to the heatingstep are stable or mostly maintained when the sample is thermallytreated at 325° C., though there is release of H₂O and CO₂.

FIG. 7 depicts ¹³C NMR spectra of bulk CoMo catalyst precursor thermallytreated at 325° C. under air and N₂. The ¹³C NMR data shown in FIG. 19provides further evidence of the complexation of organic complexingagent, e.g. glyoxylic acid to metals. The ¹³C NMR spectra were recordedunder conditions of magic angle spinning (MAS) to avoid the chemicalshift anisotropy and some dipole interactions. Aliphatic CH₂-type carbonappears in the Chemical Shift range 0-40 ppm. C—N— type carbon can alsobe observed in the range of 15 to 60 ppm. The C═O of aldehyde groups isobserved in 190-220 ppm while C+O of carboxylic groups is observed inthe range of 170-180 ppm. Aromatic carbon is normally observed in therange of 120-160 ppm. In addition, carbons in C—O and C—N groupsgenerally are observed at around 40-80 ppm. These results are in linewith FTIR data and can be explained by the complexation of metal withglyoxylic acid functional groups.

FIG. 8 depicts Raman spectra of a bulk CoMo catalyst precursor thermallytreated at 325° C. in air when the catalyst precursors are exposed tohigher temperature heat treatments in a Temperature Programmed Oxidationstudy. The top spectrum in FIG. 8 corresponds to a bulk catalystprecursor exposed to 300° C. in the presence of air. This spectrumpotentially shows some disordered CoMoO₄, but otherwise no crystallineoxides. The next spectrum shows a catalyst precursor exposed to 450° C.The signal strength for the CoMoO₄ is stronger in this spectrum. It isbelieved that this represents the beginning of agglomeration of Co andMo due to removal of carbonaceous or organic compound-based material. At550° C., excess Mo is beginning to aggregate to form a MoO₃ phase withinthe catalyst precursor. This is believed to be due to further loss ofcarbonaceous material from the precursor. Finally, at 600° C., asubstantial majority of the carbonaceous material has been removed. Atthis point, a crystalline MoO₃ phase and β-CoMo₄ phase are clearlyvisible in the spectrum, as indicated by the starred (*) peaks. ThisRaman result is consistent with X-ray Diffraction (XRD) results shown inFIG. 9.

FIG. 9 provides a comparison of XRD results between a bulk CoMo catalystprecursor (formed through thermal treatment in air at 325° C.) and thesame sample but heated to 600° C. in air for 4 hours. For the catalystprecursor heated to 325° C., which corresponds to plot a) in the figure,no identifiable crystalline phase is detected by XRD. In contrast, theXRD of the higher temperature treated sample (at 600° C., where asubstantial majority of the carbonaceous material has been removed fromthe catalyst precursor) shows definitive crystalline morphology. Thecrystalline peaks in the XRD spectra are attributed to MoO₃ (designatedwith *) and CoMoO₄ crystalline phases.

Example 8 Inclusion of Catalyst Stabilizers-Polyethylene Glycol

Several catalyst precursors and corresponding sulfided catalysts wereprepared to determine the effect of including polyvinyl alcohol in theorganic complexing agent as a stabilizer. In a large beaker under strongstirring the following components were dissolved: 242.5 gm of(NH₄)₆Mo₇O₂₄(H₂O)₄; 171.6 gm Co-acetate-tetrahydrate; and 1668 gm ofaqueous gluconic acid solution, the gluconic acid being 48.6% by weight.This resulted in a solution with a Co to Mo ratio of 1:2, and a gluconicacid to (Co+Mo) ratio of 2:1. Another solution was made wherepolyethylene glycol was added to the above solution. The amount ofpolyethylene glycol was about 20 wt % of the amount of gluconic acid.

The above solutions were allowed to dry at 55 C under stirring. Thesolutions were then further dried at 250 F. The resulting dried materialwas calcined under N₂ at 750 F for 1 hour. The resulting dried andcalcined material (the catalyst precursor) was then pressed at 30 tonsfor 10 minutes. The pressed material was then crushed to size thematerial for use in testing.

The sized materials were tested for stability by treating the materialswith a light catalytic cycle oil (LCCO) using the following procedure.First, the catalyst material sample was weighed. The sample was thenimmersed in a known weight of LCCO with stirring at 250 F for 24 hours.The LCCO was then decanted off, and the catalyst sample was solventextracted to further remove any LCCO. The catalyst was dried at 250 F,and then weighed again to determine the difference in the weight of thecatalyst sample. Under this test, the sample made without polyethyleneglycol retained only 85% of its initial weight. The catalyst sample thatincluded the polyethylene glycol had 101.8% of its initial weight,indicating that little or no catalyst weight was lost due to poorcatalyst integrity.

Example 9 Inclusion of Catalyst Stabilizers-Polyvinyl Alcohol

Several catalyst precursors and corresponding sulfided catalysts wereprepared to determine the effect of including polyvinyl alcohol in theorganic complexing agent as a stabilizer. In a large beaker under strongstirring the following components were dissolved: 242.5 gm of(NH₄)₆Mo₇O₂₄(H₂O)₄; 171.6 gm Co-acetate-tetrahydrate; and 1668 gm ofaqueous gluconic acid solution, the gluconic acid being 48.6% by weight.This resulted in a solution with a Co to Mo ratio of 1:2, and a gluconicacid to (Co+Mo) ratio of 2:1. Another solution was made where polyvinylalcohol was added to the above solution. The amount of polyvinyl alcoholwas about 25 wt % of the amount of gluconic acid.

Samples of the above solutions were allowed to dry at 130 F understirring. The solutions were then further dried at 250 F. The resultingdried material was calcined under N₂ at 750 F for 1 hour. The resultingdried and calcined material (the catalyst precursor) was then pressed at30 tons for 10 minutes. The pressed material was then crushed to sizethe material for use in the testing described in Example 10.

Additional samples of the calcined material containing the polyvinylalcohol were used to form 1/16 inch diameter extrudates. In some of theextrudates, one of three binders was mixed with the calcined materialprior to extrusion. One binder was an Si-resin that is availablecommercially from Dow Corning as “flake resin”. This binder material wasreduced in size to less than 35 mesh prior to use. Another binder wasNyacol 2034DI, which is available from Nyacol Nano Technologies. Thethird binder was Tyzor® LA, which is a lactic acid chelated Ti binderavailable from Dupont.

The four extrudates are described in Table 4 below, including themeasured BET surface area for each extrudate. The extruded samples werealso tested for stability using the method described in the Example 8.As shown in Table 4, all of the extrudates showed good stability withregard to avoiding weight loss, indicating good catalyst integritywithin the measurement error for the technique.

TABLE 4 Weight Surface Catalyst/ area Weight Trade (BET Initial AfterPercent Binder Binder Name m²/g) Weight Weight Recovered 95/5 SiO2Si-Resin 24.6 5.2185 5.1616 98.9  90/10 SiO2 Nyacol 22.6 5.2076 5.2318100.5 2034DI 95/5 TiO2 Tyzor LA 18.2 5.1921 5.215 100.4 100/0  <none><none> 2.7 5.2972 5.3172 100.4

Example 10 Activity of Stabilized Catalysts

Several of the catalyst precursor samples from Examples 8 and 9 wereevaluated for hydrodesulfurization performance in a batchwise test. Anamount of catalyst precursor was added to a vial with a testhydrocarbon. The test hydrocarbon was a hydrotreated distillate rangematerial with lighter sulfur compounds removed, leaving between 500 to700 ppm sulfur in the hydrocarbon. The amount of hydrocarbon in the vialwas roughly 10 times the weight of the catalyst. The catalyst wassulfided with a stagnant gas phase containing 10% H2S in H2 at 220 psigand 625 F for 24 hours. The hydrocarbon was then removed and replacedwith fresh hydrocarbon. Once again, the amount of hydrocarbon wasroughly 10 times the weight of the catalyst. The activity test wasperformed with a stagnant gas phase containing 1% H2S in H2 at 220 psigand 625 F for 24 hours. The sulfur level of the hydrocarbon product wascompared to the feed. This was used to determine a first order rateconstant.

In the tests, the activity of the catalyst based on the precursor samplecontaining gluconic acid and metals (no stabilizer) was used as abaseline. Table 5 shows the relative activity of the various catalystsformed using gluconic acid as the complexing agent and including eitherPVA or PEG as a stabilizer. Note that in the table “press” refers tocatalysts made by pressing the catalyst precursor under 30 tons and thencrushing to size the precursor particles. “Ext” refers to an extrudedcatalyst precursor.

TABLE 5 % HDS activity Catalyst (relative) Glu-PVA Press 122 Glu-PEGPress 123 Glu-PVA/Si Resin Ext 72 Glu-PVA/Nyacol Ext 104 Glu-PVA/TyzorExt 115 Glu-PVA Ext 102

As shown in Table 5, the stabilizer and the binders showed little or noeffect on the activity of the resulting catalyst, with the possibleexception of the catalyst formed using the Si Resin binder. In fact,many of the catalysts formed had improved activity relative to thecatalyst composed of gluconic acid and metals that did not include astabilizer or binder.

Example 11 Sulfidation of Catalyst Precursors

Improvements in catalyst stability and activity can also be achievedusing gas phase sulfidation methods at temperatures below 350° C. FIG.10 shows the catalytic activity over time for bulk metal catalysts thatwere sulfided using a conventional liquid phase sulfidation method at625° F. The bulk metal catalysts correspond to catalysts prepared usingthe procedure for Precursor B in Table 1. Catalysts sulfided at threedifferent pressures are shown. For each of the sulfided catalysts, theactivity for hydrodesulfurization decreases over time.

FIGS. 11 a and 11 b provide a comparison of a conventionally gas-phasesulfided catalyst with a catalyst sulfided at a temperature of less than350° C. using a 10% H₂S/H₂ mixture at atmospheric pressure. In FIGS. 11a and 11 b, catalyst precursors are exposed to gas-phase sulfidingconditions for extended periods of time. In each figure, one of thecurves shows the temperature profile during the sulfidation, while theother curve shows the weight loss of the catalyst during sulfidation. Asshown in the figures, the catalyst sulfided at 325° C. eventuallystabilizes with regard to weight loss, indicating that a stable catalysthas been formed. The catalyst sulfided at 400° C., however, continues tolose weight over the full scope of the sulfidation procedure.

FIG. 12 demonstrates that the sulfidation temperature also affects themorphology of the catalyst formed during gas-phase sulfidation. FIG. 12shows TEM micrographs of the catalysts described in FIG. 11 that wereformed by gas-phase sulfidation at 325° C. and 400° C. The catalystformed with sulfidation at 325° C. shows substantially smaller stackheights for the molybdenum sulfide on the catalyst surface. In general,smaller stack heights are believed to be favorable for increasing theactivity of a hydrodesulfurization catalyst.

Example 12 Preparation from Solid Mixtures

The catalyst precursors of the claimed invention can also be preparedfrom solid mixtures. In the following examples, catalyst precursors wereprepared by mixing and grinding the solids of cobalt acetate, AHM, andglyoxylic acid monohydrate. For the first example, the ground mixturewas then calcined at 325° C. for 4 hours and showed partiallycrystallized phases in an XRD analysis. In another preparation, aftergrinding the mixture was placed in an autoclave for 24 hours at atemperature of either 80° C. or 95° C. The precursors were then calcinedat 325° C. for 4 hours. The resulting catalyst precursors had aprimarily amorphous XRD pattern. In still another preparation, the mixedsolids were ground in the presence of a water mist and then calcined.The water mist during grinding added roughly 10 wt % of water to themixed solids. This resulted in a precursor with a substantiallyamorphous XRD pattern. The various precursors are described in Table 6below.

TABLE 6 BET SA Solid by TGA C Content Solid Mixing Samples (m²/g) (wt %)(wt %) Grinding <1 70.6 19.2 Grinding and autoclave at 80° C. 10.4 63.520.3 Grinding and autoclave at 95° C. 15.4 60.9 20.6 Grinding andmisting <1 69.7 21.1

Example 13 Bulk CoMo-C Samples with Various Organics

Catalyst precursors were prepared using the organics indicated in thetable below in place of glyoxylic acid. Otherwise, the precursors wereprepared according to the method in Example 1. The ratio of organic tometal is 4.8 in each example except for the second ketoglutaric acidexample, where the ratio was 2.4. Note that the acetic acid and formicacid represent comparative examples, due to the low carbon content ofthe resulting precursor.

Solid by BET SA TGA C Content Precursors (m²/g) (wt %) (wt %) XRDGlyoxylic acid <1 66.3 21.9 Amorphous Acetyl <1 73.3 20 Amorphousacetonate Maleic acid <1 50.0 32 Primarily amorphous, some crystallinecharacter (MoO₃ phase) Acetic acid 22 98.7 0.35 Crystallized (CoMoO₄phase) Formic acid 19 100.5 0.14 Crystallized (MoO₃ phase) Gluconic acid<1 24.1 57.9 Amorphous Glucose <1 24.1 60.4 Amorphous Ketoglutaric <not46.3 Amorphous acid measured> Ketoglutaric <not 37.4 Amorphous acid(2.4) measured>

1. A bulk metallic catalyst precursor composition comprising a GroupVIII metal, a Group VIB metal, and from about 10 wt. % to about 60 wt. %of an organic compound-based component, the catalyst precursorcomposition having a surface area of 50 m²/g or less based on BET,wherein the organic compound-based component is based on at least oneorganic complexing agent and at least one stabilizer.
 2. A sulfided bulkmetallic catalyst comprising a sulfided form of the bulk metalliccatalyst precursor composition of claim
 1. 3. The sulfided bulk metalliccatalyst of claim 2, wherein gas-phase sulfidation at a temperature of350° C. or less is used on the bulk metallic catalyst precursor to formthe sulfided bulk metallic catalyst.
 4. A sulfided bulk metalliccatalyst comprising a Group VIII metal, a Group VIB metal, and at leastabout 10 wt. % carbon, wherein the catalyst is formed by sulfiding acatalyst precursor composition comprising a Group VIII metal, a GroupVIB metal, and from about 10 wt. % to about 60 wt. % of a organiccompound-based component, the catalyst precursor composition having asurface area of 50 m²/g or less based on BET, wherein: (i) the organiccompound-based component is based on at least one organic complexingagent and at least one stabilizer; (ii) the bulk metallic catalyst isformed by gas-phase sulfidation at a temperature of 350° C. or less; or(iii) both (i) and (ii).
 5. The sulfided bulk metallic catalyst of claim4, wherein the Group VIII metal is nickel or cobalt, and wherein theGroup VIB metal is molybdenum or tungsten.
 6. The sulfided bulk metalliccatalyst of claim 5, which contains regions of MeS₂ having stack heightsaveraging from about 1.1 to 2.5, wherein Me represents a Group VIBmetal.
 7. The sulfided bulk metallic catalyst of claim 6, wherein thestack height is about 2.2 or less.
 8. The sulfided bulk metalliccatalyst of claim 7, wherein the stack height is about 2.0 or less. 9.The sulfided bulk metallic catalyst of claim 4, wherein the surface areais less than about 40 m²/g.
 10. The sulfided bulk metallic catalyst ofclaim 9, wherein the surface area is less than about 30 m²/g.
 11. Thesulfided bulk metallic catalyst of claim 10, wherein the surface area isless than about 16 m²/g.
 12. The sulfided bulk metallic catalyst ofclaim 11, wherein the surface area is less than about 10 m²/g.
 13. Thesulfided bulk metallic catalyst of claim 4, wherein the surface area isat least 0.1 m²/g.
 14. The sulfided bulk metallic catalyst of claim 4,wherein the organic compound-based component is based on an organic acidand a stabilizer.
 15. The sulfided bulk metallic catalyst of claim 4,wherein the stabilizer is polyethylene glycol, polyvinyl alcohol, or acombination thereof.
 16. The sulfided bulk metallic catalyst of claim 4,further comprising an additional transition metal.
 17. The sulfided bulkmetallic catalyst of claim 16, wherein the additional transition metalis Co, Ni, or Zn.
 18. The sulfided bulk metallic catalyst of claim 4,wherein the catalyst precursor is extruded with a binder to form anextruded composition having a surface area of 30 m²/g or less.